A molecular organic carbon isotope record of miocene climate changes
- Chevron Petroleum Technology Co., La Habra, CA (United States)
- Netherlands Institute of Sea Research, Texel (Netherlands)
- Australian Geological Survey Organization, Canberra (Australia)
The difference in carbon-13 ([sup 13]C) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in [sup 18]O ([delta][sup 18]O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes ([delta][sup 13]C = 25.4 [+-] 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound C[sub 35] hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing [sup 13]C concentrations in Middle and Late Miocene samples ([delta][sup 13]C = 29.5 to [minus]31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone.
- OSTI ID:
- 7201710
- Journal Information:
- Science (Washington, D.C.); (United States), Vol. 263:5150; ISSN 0036-8075
- Country of Publication:
- United States
- Language:
- English
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